JPH09244043A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which pixel defects such as short circuit between pixels whose main cause is residues of a wrapping material and so forth are excluded by allowing a transparent conductive electrode to be formed even on the protruding part of the thin film transistor of a pixel part to suppress the generating of residues of the wrapping material. SOLUTION: In this liquid crystal display device, signal lines 7A, 7B and scan lines 8AS, 8B are arranged and provided and a TFT is arranged and provided at intersection parts of them. Then, 1 Poly (the drain) of the TFT is connected to the signal line 7A via a first contact hole 9, the gate of the TFT is connected to the scan line 8A and the source of it is connected to a transparent conductive film electrode 20 via second contact hole 10. The transparent conductive film electrode 20 is formed by being made to avoid the protruding part of the TFT as in the shown figure so as not to cause the difference in level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, a transparent conductive film electrode is formed so as to avoid a convex portion on a driving substrate to suppress generation of rubbing material residue in a rubbing process. The present invention relates to a liquid crystal display device whose quality is stabilized.

[0002]

2. Description of the Related Art Liquid crystal display devices are characterized by a flat structure and low power consumption, and are being put to practical use and becoming widespread in electronic equipment equipped with liquid crystal display devices such as liquid crystal projectors and laptop personal computers, and televisions. FIG. 4 is a diagram showing a basic configuration of a liquid crystal display device according to the present invention. The liquid crystal display device 1 in the figure is roughly composed of a drive substrate 2 and a counter substrate 3. Scanning lines and signal lines, which are insulated from each other, are formed on the drive substrate 2, thin film transistors (not shown) for driving each pixel are formed at the intersections thereof, and the transparent conductive film electrodes 2A and the alignment film are formed. 2B is formed. Although not shown, the counter substrate 3 is provided with R, G, and B color filters, a transparent conductive film electrode 3A, and an alignment film 3B in the case of a color liquid crystal panel. A liquid crystal display device having such a structure is called an active matrix type. The liquid crystal display device which is the object of the present invention is not limited to this structure and is merely an example.

The driving substrate 2 and the counter substrate 3 are manufactured in their respective manufacturing processes, and then are arranged to face each other with a predetermined gap therebetween, and the spacers 4 are sandwiched therebetween and joined by a seal material 5. After that, the liquid crystal 6 is injected from an injection hole (not shown), and two polarizing plates (not shown) are integrally laminated on both surfaces of these glass substrates to complete the liquid crystal display device 1 having the above configuration.

Next, the structure of one pixel area in the liquid crystal display device will be described with reference to FIG. This display device
H shift register (not shown) arranged on the drive substrate 2
Signal line 7 that is connected to and inputs a video signal to each pixel section
A and 7B, a scanning line 8A that is connected to a V shift register (not shown) and supplies a scanning pulse to each pixel portion,
8B is interpolated. For example, a thin film transistor (hereinafter, simply referred to as “TFT”) for switching and driving each pixel electrode is provided at the intersection of the signal line 7A and the scanning line 8A, and 1 Poly of the TFT is provided.
The (drain) is connected to the signal line 7A through the first contact hole 9, the gate of the TFT is connected to the scanning line 8A, and the source is connected to the above-mentioned transparent conductive film electrode 2A through the second contact hole 10. ing. Here, the transparent conductive film electrode 2A according to the present invention is the channel portion 1 of the TFT.
Since it is formed over one portion, it is formed to be higher than other portions. Note that the liquid crystal display device in the figure shows one of the pixels for the sake of simplicity.

The operation of the liquid crystal display device having such a configuration will be briefly described with reference to FIG.

Video signals and various control signals input from an external IC are input to an H shift register and a V shift register (both not shown). The TFT controls the video signal supplied via the signal line 7A in response to the scanning pulse supplied from the scanning line 8A, and supplies it to the transparent conductive film electrode 2A. In the transparent conductive film electrode 2A, the liquid crystal 6 is twisted and inverted in the voltage application direction by the video signal controlled for each pixel portion, and information is displayed on the liquid crystal display device by utilizing the optical rotatory power of the liquid crystal 6.

Furthermore, the rubbing method of the conventional liquid crystal display device will be described by exemplifying the rubbing process in the conventional liquid crystal display device in FIG. The rubbing step is a step of rubbing the surface of the alignment film in a certain direction to facilitate the alignment of the liquid crystal molecules in the rubbing direction in order to enhance the alignment of the liquid crystal 6. This rubbing process is carried in by carrying in the substrate to be processed by a conveyor and moving the substrate in the direction of the arrow while rotating the roller 13 around which the rubbing material 12 such as felt is wound. The drive substrate that has completed the rubbing process is again delivered by the conveyor and carried out to the next process. Since the rubbing material 12 is a consumable part, it is regularly replaced and used.

By the way, since the transparent conductive film electrode 2A of the conventional liquid crystal display device is formed over the convex portion of the thin film transistor in the pixel portion, by performing such a rubbing process, the rubbing process is performed or the rubbing process is performed. After the process, the rubbing material is scraped off at the edge of the transparent conductive film electrode,
A rubbing material residue (hereinafter, simply referred to as “buff residue”) as shown in FIG. 6B is laminated. The buffs stacked in this way cause short-circuiting between pixels, resulting in poor alignment and defects such as bright spot defects. Further, since the rubbing material 12 is scraped more than necessary at the edge portion of the transparent conductive film electrode 2A, the rubbing material 1
There is a problem that the replacement frequency of 2 increases and the manufacturing cost rises.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its problem is that the transparent conductive film electrode is formed also on the convex portion of the thin film transistor in the pixel portion. An object of the present invention is to provide a liquid crystal display device which suppresses the generation of material dust and eliminates a short circuit between pixels mainly caused by the generation of dust, thereby stabilizing the display quality.

[0010]

In order to solve the above-mentioned problems of the present invention, the following means have been taken. That is, as a basic configuration of the liquid crystal display device of the present invention, a drive substrate including a transparent conductive film electrode (pixel portion) arranged in a matrix on the substrate and a thin film transistor for driving the transparent conductive film electrode is provided. In the liquid crystal display device having the transparent conductive film electrode formed by avoiding the convex portion of the thin film transistor, a rubbing process defect in the convex portion of the thin film transistor (short circuit defect mainly caused by rubbing material residue generated during the rubbing process, etc.) ) To avoid.

As an applied configuration of the liquid crystal display device of the present invention,
The transparent conductive film electrode, in addition to a display area for displaying an image,
An image formed around the display region is also formed in a dummy pixel region that does not display, so that the transparent conductive film electrode in the display region is not affected by the rubbing process defect.

According to the liquid crystal display device of the present invention, the transparent conductive film electrode formed on the driving substrate is formed so as to avoid the convex portion of the thin film transistor and prevent a step. Accordingly, it is possible to suppress the defective rubbing process in the convex portion of the thin film transistor, that is, the occurrence of buffing in the rubbing process, and to suppress the occurrence of short circuits between pixels and the occurrence of pixel defects due to the buffing. Further, since the transparent conductive film electrode is not formed on the convex portion of the thin film transistor, the rubbing material is not scraped more than necessary at the edge portion of the transparent conductive film electrode, and the replacement time of the rubbing material can be extended, Manufacturing cost can be reduced and production efficiency can be improved. Further, by forming the transparent conductive film electrode formed on the driving substrate also in the dummy pixel area where the image is not displayed, buff residue does not enter the display area, and pixel defects such as short circuit between pixels can be eliminated. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

First Embodiment First, the configuration of a first embodiment of the liquid crystal display device of the present invention will be described with reference to FIG. FIG. 1 is a plan view showing one pixel region in the first embodiment of the liquid crystal display device of the present invention. It should be noted that parts common to those described in the related art are designated by the same reference numerals.

This display element is connected to an H shift register (not shown) provided on the drive substrate 2, and
Signal lines 7A and 7B for inputting a video signal to each pixel portion are connected to the V shift register, and scanning lines 8A and 8B for supplying a scanning pulse to each pixel portion are interpolated. Then, for example, a TFT for switching and driving each pixel portion is arranged at the intersection of the signal line 7A and the scanning line 8A, and 1Poly (drain) of the TFT is connected to the signal line 7A through the first contact hole 9. The gate of the TFT is connected to the scanning line 8A, and the source is connected to the transparent conductive film electrode 20 via the second contact hole 10. The transparent conductive film electrode 20, which is a feature of the present invention, is formed so as to avoid the channel portion 11 of the TFT as shown in FIG.

On the other hand, the cross-sectional structure of the liquid crystal display device shown in FIG. 2 (a) is 1 Poy formed on a washed substrate.
A first PSG (phosphosilicate glass) 21 and a second PSG 22 (which may be NSG) formed after patterning 2 Pory and 2 Pory formed through a gate oxide film or the like after patterning 1 Poly, such a T
Avoid the convex portion of the FT, for example, the gate electrode of the TFT, the storage capacitor and the signal line (not shown), and the ITO (Indiu
(m-Tin Oxide) film or the like, and the transparent conductive film electrode 20 of the present invention, and an alignment film (not shown) such as a polyimide film or polyvinyl alcohol coated and formed on the transparent conductive film electrode 20. .

The liquid crystal display device of the present invention having the above structure is transferred to the rubbing process. In the rubbing process, as described above, the roller 13 wound with the rubbing material 12 is rotated in a predetermined direction and moved in the arrow direction while the rubbing material 12 is being moved.
The surface of the alignment film of the liquid crystal display device is rubbed by a predetermined direction. The drive substrate for which the rubbing process has been completed is again delivered by the conveyor and carried to the next step.

Thus, the transparent conductive film electrode 20 of the present invention
Is not formed on the convex portion of the TFT,
As shown in (b), even if the rubbing process is performed, the rubbing material is not scraped at the edge portion of the transparent conductive film electrode 20 during the rubbing process or after the rubbing process, and buff residue does not occur. As a result, it is possible to suppress the occurrence of short circuits between pixels and the occurrence of pixel defects, which are mainly caused by the stacked bass. Further, since the rubbing material 12 is not shaved more than necessary at the edge portion of the transparent conductive film electrode 20, the replacement time of the rubbing material 12 can be extended and the production efficiency can be improved.

Second Embodiment In addition to the first embodiment, the second embodiment similarly forms a transparent conductive film electrode in a dummy pixel region where an image is not displayed to suppress the occurrence of buffs in the display region. This is an example, which will be described with reference to FIG. FIG. 3 is a sectional view showing the basic structure of the second embodiment of the liquid crystal display device of the present invention.

As shown in the figure, the liquid crystal display device of this embodiment is roughly divided into a display area 23 for displaying an image and a dummy pixel area 24 formed in the peripheral portion of the display area 23 and not displaying an image. The display area 23 and the dummy pixel area 24 include the TFT formed in each pixel portion and the TFT
A first PSG 21 for covering the wiring, a wiring electrode 25 made of, for example, Al and patterned on the first PSG 21, and PSG, NSG, S for covering these.
Second PSG 22 made of iO ₂ , SiN, etc., planarizing film 2
6, the transparent conductive film electrode 20 formed on the display region 23 while avoiding the convex portion of the TFT, and the T on the dummy pixel region 24.
Dummy transparent conductive film electrode 2 formed avoiding the convex portion of FT
7, 28.

The liquid crystal display device of this embodiment having the above structure is
After applying an alignment film (not shown), the rubbing process is performed. In the rubbing process, as described above, the rubbing material 1
The two wound rollers 13 are rotating and advancing in the direction of the arrow, and the rollers 13 rub the surface of the liquid crystal display device in a certain direction.

As described above, the liquid crystal display device of this embodiment is
At the same time as forming the transparent conductive film electrode 20 in the display area 23, the dummy transparent conductive film electrodes 27, 2 are formed on the dummy pixel area 24.
8 is formed, the buff residue can be removed before rubbing the display area 23 in the rubbing process. That is, since the buff residue is generated only at the initial stage when the rubbing material 12 and the surface of the liquid crystal display device start to contact each other, the dummy transparent conductive film electrodes 27 and 2 are formed.
The generation of buffs is suppressed at the time when 8 is passed, the influence of the buffs is not exerted on the transparent conductive film electrode 20 in the display region 23, and it is possible to suppress the short circuit between pixels and the generation of the pixel defect due to the buffs.

The present invention is not limited to the above embodiment,
Various embodiments can be adopted. For example, in the present embodiment, an example in which an ITO film is used for the transparent conductive film electrode has been illustrated, but another transparent conductive film electrode such as SnO ₂ may be used, and the drive substrate is not limited to the above-mentioned configuration. Further, the first and second embodiments may be implemented individually or in combination. Further, needless to say, the present invention can be developed into various forms without being limited to the above-described embodiments.

[0024]

As described above, according to the liquid crystal display device of the present invention, the transparent conductive film electrode formed on the driving substrate is formed so as to avoid the convex portion of the thin film transistor and not generate a step. I chose As a result, it is possible to suppress the rubbing failure in the convex portion of the thin film transistor, that is, the occurrence of buffs in the rubbing process, and the occurrence of pixel defects such as short circuits between pixels due to the buffs.
Further, since the transparent conductive film electrode is not formed on the convex portion of the thin film transistor, the rubbing material is not scraped more than necessary at the edge portion of the transparent conductive film electrode, the rubbing material replacement time can be extended, and the manufacturing cost can be reduced. There is an effect that it can be reduced to improve the production efficiency.

Further, according to the liquid crystal display device of the second invention, the transparent conductive film electrode formed on the drive substrate is formed also in the dummy pixel region other than the display region where the image is not displayed. This prevents buffs from entering the display area, and has an effect of eliminating pixel defects such as a short circuit between pixels.

[Brief description of drawings]

FIG. 1 is a plan view showing one pixel region in a first embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a diagram showing a rubbing process in the liquid crystal display device of the present invention, in which (a) is a cross-sectional view during the rubbing process,
(B) is a cross-sectional view after the rubbing step.

FIG. 3 is a cross-sectional view showing the basic configuration of a second embodiment of the liquid crystal display device of the present invention.

FIG. 4 is a schematic sectional view showing a basic configuration of a liquid crystal display device according to the present invention.

FIG. 5 is a plan view showing one pixel region in a conventional liquid crystal display device.

FIG. 6 is a diagram showing a rubbing process in a conventional liquid crystal display device, (a) is a cross-sectional view during the rubbing process,
(B) is a cross-sectional view after the rubbing step.

[Explanation of symbols]

1 ... Liquid crystal display device, 2 ... Drive substrate, 3 ... Counter substrate, 4 ...
Spacer, 5 ... Sealing material, 6 ... Liquid crystal, 7A, 7B ... Signal line, 8A, 8B ... Scan line, 9 ... First contact hole,
10 ... 2nd contact hole, 11 ... Channel part, 12
... rubbing material, 13 ... roller, 2A, 20 ... transparent conductive film electrode, 21 ... first PSG, 22 ... second PSG, 23 ...
Display area, 24 ... Dummy pixel area, 25 ... Wiring electrode, 2
6 ... Planarizing film, 27, 28 ... Dummy transparent conductive film electrode,

Claims (3)

[Claims] 1. A liquid crystal display device having a drive substrate including transparent conductive film electrodes arranged in a matrix on a substrate and thin film transistors for driving the transparent conductive film electrodes, wherein the transparent conductive film electrodes are A liquid crystal display device, characterized in that a rubbing process defect in the convex portion of the thin film transistor is avoided by forming while avoiding the convex portion of the thin film transistor. 2. The rubbing process defect in the transparent conductive film electrode in the display region is avoided by forming the transparent conductive film electrode in a display region displaying an image and a dummy pixel region not displaying an image. The liquid crystal display device according to claim 1. 3. The projection of the thin film transistor is at least one location on a gate electrode of the thin film transistor, on a signal line, and on a storage capacitor formed in the vicinity of the thin film transistor. Item 3. The liquid crystal display device according to item 2.